A refrigerating system is widely used in fields such as food storage and air conditioning. As shown in FIG. 2, a refrigerating system 40 of the prior art is constituted by including a compressor 41, a condenser 42, a liquid receiver 43, an expansion valve (depressurizing unit) 44, and an evaporator (chiller) 45.
Moreover, ammonia and fluorocarbon gas which are very volatile liquids are used for refrigerants. The ammonia has a low temperature of −33.3° C. at the atmospheric pressure and when this cold liquid becomes a gas, it wrests heat from the surrounding area to refrigerate the area.
In the case of the refrigerating system 40 of the prior art, the compressor 41 sucks in and compress a cold gas G1 gasified by the evaporator 45 and compresses to generate a high-temperature high-pressure gas G2. The compressed gas G2 is cooled and condensed by water or air in the condenser 42 to generate a liquid L1. The refrigerant L1 becoming a liquid is temporarily stored in the liquid receiver 43 and then sent to the expansion valve 44 set to the entrance of the evaporator 45.
The high-temperature and high-pressure refrigerant L1 is expanded in the expansion valve 44 to depressurize it. When the refrigerant L1 passes through the expansion valve 44, some of the refrigerant L1 is evaporated and reduced in temperature to become a low-temperature and low-pressure refrigerant L2. The refrigerant L2 is evaporated in the evaporator 45 to wrest heat from the surrounding area of the evaporator 45, and when evaporated, it cools the surrounding area of the evaporator 45, and generates a refrigerating action.
However, the conventional refrigerating system uses a single fluid such as ammonia or fluorocarbon gas as a refrigerant for forming a refrigerating cycle and compresses the whole quantity of the refrigerant which is a single fluid, in a gas state by the compressor. Therefore, there are problems that the required motive power of the compressor increases, the system increases in size, and the power consumption increases.
That is, the “coefficient of performance (COP)” indicating the refrigeration efficiency obtained by dividing the refrigerating capacity by the thermal equivalent of compression, particularly, the “actual coefficient of performance =refrigerating capacity (kW)/motor(kW)” obtained by dividing the refrigerating capacity by the heat quantity corresponding to the output of a motor for operating a refrigerator deteriorates.
However, there is gas hydrate used for Japanese Patent Laid-Open Nos. 157005/1982, 340035/1992, 58646/1994, and 2001-10990 as the motive power source of a turbine and the like, cold heat storing material, and gas occlusion substance.
This gas hydrate is referred to as a hydrate clathrate compound or a gas clathrate compound, which is obtained by mixing a gas such as low-class carbon hydride with a liquid (hydrate) such as water. In the case of the decomposition heat of this gas hydrate, it is known that the decomposition heat in terms of the unit mass of gas is very large and becomes approx. 1.3 times larger than that of water.
The present invention is made to solve the above problems by obtaining the above knowledge, and its object is to provide a refrigerating method and a refrigerating system capable of using a large decomposition heat absorbed, when decomposing gas hydrate by utilizing gas hydrate as the refrigerant of a refrigerating system and capable of greatly decreasing the motive power necessary for the refrigerating system by boosting the liquid components generated due to decomposition of gas hydrate by a pump, compressing only the gas components by a compressor, and thereby, decreasing the gas quantity to be compressed by the compressor.